1. Field of the Invention
The present invention relates to a metering device. In a particular aspect, the invention relates to a metering device which is particularly suitable for distributing, in measured amounts, granular materials such as granular pesticidal materials.
2. Description of the Prior Art
Pesticidal materials can be applied in various forms such as in powder or granular form. Generally, when applying pesticidal materials in powder form, the application is usually performed from a "backpack" applicator. An example of such an applicator is one which is obtainable from F. Giacomo and Luigi Carpi, 42028 Poviglio Reggio E. Italy under the tradename "SPEEDAIR CIDUE". This type applicator is normally provided with a housing and two superimposed plates that are disposed within the housing. Each of the plates are provided with openings which are adapted to be in position depending on the position of an operating handle ranging from partial to full registry, i.e., adjustable with respect to each other whereby powdered material, introduced into the housing is permitted to fall by gravity, through each respective opening to the bottom of the housing. Air from a separate air bellows directs the material out of the unit via a flexible tube to the treatment site. Unfortunately however, there is in effect no actual metering of the material with this type of device. Moreover, this type device is not entirely satisfactory when attempting to distribute granular materials.
In short, the disadvantages of this type of device include inconsistent dosages; the inability to stop the material flow unless the operating handle is in a certain position and finally the insensitive adjustment of calibration rates.